This invention relates to the forming, shaping, control and use of fluids, fibers and particles such as for example the formulation of a pesticide, shaping it into droplets, and the distribution of the droplets over a field to control pests or the formulation of a soluble chitosan, the shaping of it into fibers or mats or sheets and the use of the fibers, mats and sheets such as for example in biomedical applications.
It is known to shape and spray fluids and suspensions with spraying systems. In some applications, the fluids and suspensions are formed into droplets or aerosols and sprayed by the spraying systems. In other applications, the fluids form fibers, or powders or particles.
One use of such spraying systems is to apply agricultural inputs to agricultural fields. Commonly, the spraying systems include vehicles that carry the agricultural inputs and spray equipment that apply from the vehicle through fixtures supported by booms on the vehicle. The spray equipment may includes pumps for air and for the agricultural inputs.
In one type of prior art spaying system for this use, the vehicles used to spray the agricultural fields carry large volumes of diluted active ingredients because it is difficult to spray more concentrated forms of the active ingredient and may be outfitted with a high pressure source of air and/or fluid requiring one or more relatively large pumps to spray the liquid containing the active ingredient because high pressure air and/or liquid pressure is needed to form the desired spray and a large volume of liquid containing the active ingredient must be pumped. In some such systems, the fixtures or nozzles are relatively high above the target for the spray to permit the cone of fluid to provide an adequate area of coverage with the spray. Usually the cone angle is determined by the nozzle and has a limited angle. One reason for diluting the active ingredient is because existing spray equipment used in agriculture cannot spray viscous material with the desired size drops and drop distribution and accurate low volume equipment is not economically available.
The prior art spray systems have several disadvantages such as for example: (1) they require vehicles carrying the agricultural inputs to carry heavier than desirable weights of agricultural inputs with the associated water carrier; (2) they require the replenishment of the supply of agricultural inputs carried by the spray vehicles periodically, thus increasing the time and expense of spraying; (3) they cannot be used for the application of some beneficial microbes because the microbes are killed by the high pressure used in the prior art techniques for application of agricultural inputs; (4) the low viscosity agricultural inputs drift when sprayed; (5) some of the carriers used for dilution, such as water, have high surface tension and form beads on contact rather than spreading such as over a leaf; (6) the low viscosity sprayed drops tend to break up because of low shear resistance, thus forming smaller drops that are subject to increased drift; (7) some of the carriers used for dilution, such as water, have unpredictable mineral content and pH variations; (8) the angle of the cone of sprayed fluid from the nozzles is small thus requiring the nozzle to be positioned at a high elevation above the spray target to obtain adequate coverage but the high elevation increases drift; (9) the use of some carriers for dilution in some circumstances causes precipitation of active ingredients (10) the prior art systems cannot effectively spray some particles such as particles that have absorbed active ingredients in them that are to be released at a later time and/or environmental condition or over a timed interval; (11) the angle over which the spray is released for hydraulic nozzles is less flexible in prior art nozzles resulting in target coverage limitations; (12) the conventional high pressure hydraulic atomization nozzles used result in excessive nozzle wear and consequential variations in the distribution rate and frequent changes in nozzles; and (13) sprayer vehicle speed is limited by the pressure because higher pressures are required for high rates of application and there are pressure limitations on the system components.
Spray apparatuses are known for spraying viscous materials. This type of spraying apparatus has not generally been adapted for use in spraying agricultural inputs. Moreover, the known spraying apparatus for spraying viscous materials is not readily adjustable for different size droplets or particles or viscosity of the droplets and is not equipped with a convenient mechanism to adjust drop size or pattern or viscosity of the drops in the field as appropriate and thus reduce drift by conveniently adjusting drop size and viscosity in accordance with circumstances such as wind speed, distance of spray fixture from the spray target or speed such as for example by ground vehicle or airplane.
It is known from U.S. Pat. No. 6,589,579 B2 to form small particles by flowing a hardenable liquid through small needles. The needles are mounted near an opening in a chamber containing pressurized gas so that the hardenable liquid flows from the needle while at the same time pressurized gas flows through the opening in the chamber parallel to the liquid flowing from the needle. This results in the liquid being formed into thin microjets, becoming unstable and breaking into small particles. This process is used to form encapsulated foods and the like and to form small hollow spheres. This patent does not disclose the making of nanofibers. The process disclosed in this patent has the disadvantages of being limited to small encapsulated particles and low volume production.
It is known from U.S. Pat. Nos. 5,520,331; 6,598,802 B2; and 6,241,164 B1 to form bubbles and to burst the bubbles to form a chemical mist for fire suppression. It is suggested that the disclosed apparatus could be used for other applications requiring a chemical mist including the application of chemicals to plant life.
The apparatuses and process disclosed in these patents have a disadvantage in that they are not adapted for use with viscous materials nor to adjust drop size and distribution in a manner suitable for the application of many agricultural inputs.
It is known from U.S. Pat. No. 5,680,993 to form drops of agricultural inputs at low pressures by pumping a stream of agricultural input from the center of a stream of air in the same direction as the flow of air. Other jets of air are directed at the stream of agricultural inputs from the side. This prior art device has the disadvantage of requiring the agricultural input to be pumped through a narrow conduit under pressure into the stream of air and thus is limited in handling viscous agricultural products, semisolids and mixtures of semisolids and particles.
It is known to form nanofibers using electrospinning techniques. In the prior art method of forming nanofibers by electrospinning, fluids are drawn into small diameter fluid ligaments or columns and dried to form the fibers. The prior techniques for forming nanofibers have disadvantages in that they are not suitable for forming nanofibers of some materials because of limitations on conductivity, dielectric constant and surface tension. The electric potential to adequately draw the viscous fluid is close to the break down potential of air and the system causes corona discharge before the fibers can be formed.
It is known to use chitosan as a biodegradable structural member, particularly in medical applications. Chitosan is a hydrolyzed product of chitin, that is antifungal, anti-allergic, anti-tumor, and immune-activating. Chitin is a common naturally occurring material formed of glucosamine and N-acetylglucosamine units, and chitosan is obtained by a chitin hydrolysis process. Chitosan fibers and mats of chitosan are thus formed by electrospinning of chitosan solutions. However, conventional chitosan solutions are undesirable for electrospinning because of their high conductivity, viscosity and surface tension. Other difficulties with putting chitosan in solution are toxicity of some solutions. While chitosan has long been known to form viscous gels in carboxylic acids such as acetic, formic, and ascorbic acid, as well as in mineral acids, it is not soluble in either water or basic solutions. In addition, all organic solvents with the notable exception of a 3 to 1 mixture of dimethyleformamide and dinitrogen tetroxide, and some fluorine-containing solvents, which are both costly and toxic are also unable to dissolve chitosan regardless of its degree of deacetylation (DA).
It is also known from U.S. Pat. No. 6,695,992 B2 to form nanofibers by directing an air flow against a film on a flat surface. However, with the method described in U.S. Pat. No. 6,695,992, only relatively short fibers have been obtained and at times the fibers stick to one another. When attempts have been made to keep the fibers separate by electrodynamic force, the fibers stuck to each other rather than being kept separate.
In certain applications, fiber deposits require a specific orientation, and there have been several prior art techniques to induce such type of structural ordering. Tanase, et al., Magnetic Trapping and Self-Assembly of Multicomponent Nanowires, “Journal of Applied Physics”; May 15, 2002, v. 91, issue 10, pp. 8549-8551, discloses a technique that uses magnetic fields to align suspended nickel nanowires in solution. In electrospinning, grounded wheel-like bobbin collectors were used to align polyethylene oxide nanofibers. This method has one disadvantage, namely that it is impossible to adjust the rotational speed of the collector to ensure that fibers remain “continuous” i.e. without snapping due to a mismatch between the fiber deposition rate and the bobbin's angular velocity.
It is known from Chitosan-Coating of Cellulosic Materials Using an Aqueous Chitosan-CO2 Solution Sakai et al “Polymer Journal”, v. 34, n. 3, pp 144-148 (2002) to coat paper and fibers with chitosan prepared in part by bubbling carbon dioxide through a chitosan gel. The chitosan gel is prepared by dissolving chitosan in one percent acetic acid, putting the solution into a sodium hydroxide solution to form a gel, washing the gel with water and bubbling CO2 through the gel. The carbon dioxide was to dissolve the chitosan—not to remove acid and there is no suggestion of using carbon dioxide to remove the acid.
Fluid drilling systems that supply a mixture of gel and seeds onto an agricultural field are known. One prior art fluid drilling apparatus uses impeller pumps or peristaltic pumps or the like to extrude a mixture of gel and seeds. The seeds are germinated prior to planting. Such processes are shown in United Kingdom patent 1,045,732 and in U.S. Pat. No. 4,224,882. These apparatuses have a tendency to distribute seeds with irregular and poorly controlled spacing between the seeds and under some circumstances damage seeds. Moreover, they are prone to plugging from the accumulation of seeds in tubes used in the apparatus.
It is known that an internal delivery tube diameter to seed diameter ratio of at least 3 to 1 is desirable for delivering gel seed mixtures to a planter row. Moreover, when moving fluid gel seed mixtures in a tube, the seeds are propelled much faster at the center line of the tube than at the side walls as a function of the laminar flow conditions which exist for gels having a viscosity that suspends seeds. Because the tube-seed ratio must be so large, adequate flow for fluid drilling of large seeds requires inordinate amounts of fluid and very large pumps to get the seeds delivered. The requirements for pump size and fluid amounts increase exponentially as seed diameter increases linearly for the systems currently in use.
It has also been shown with peristaltic pump systems at seed densities in gel where the volume of gel to volume of seed ratio is less than about four, frequent blocking of the pump inlet port by seeds is experienced. The same limitations apply to piston or air displacement systems. Gels continue to extrude while the seeds pile up at the port as the amount of seed in the mixture increases.
These disadvantages limit the flexibility of the current fluid drilling hardware for delivering large seeds, for using smaller quantities of gel to reduce gel cost per acre and for reducing the volume of gel that must be carried by the planting equipment. Further, this ratio limitation impacts on the use of optimal concentrations of treatment chemicals or microorganisms in gels while still being able to use low total amounts of treatment per acre through using for example, gel to seed ratios of 1 to 1. Thus the physics of dispensing seeds suspended in non-Newtonian fluids imposes strict limitations on the utility of the current commercial fluid drilling hardware.
Attempts to reduce this problem have relied in some circumstances on seed detectors, and counters or timers that attempt to control the rate of dispensing of seeds in accordance with the rate of travel of a tractor. Such an approach is disclosed in U.S. Pat. No. 3,855,953. This approach has not entirely solved the problem in a satisfactory manner.
It is also known to use screw type mechanisms that receive and capture seeds carried along by a fluid such as air or water and emit the seeds one by one. Such an apparatus is disclosed in U.S. Pat. No. 2,737,314 to Anderson. This apparatus has a disadvantage of damaging seeds and being relatively complicated and unreliable.
Augers are known for conveying matter from place to place but such augers have not been successfully adapted up to now to fluid drilling apparatuses. Some such augers have utilized a stream of air at an angle to the flow of material to break off controlled lengths of the material and such an apparatus is disclosed in U.S. Pat. No. 3,846,529. However, this patent does not disclose any method of fluid drilling.
The augers used in the prior art are not designed in a manner adequate to separate seeds, to avoid plugging of the conduits carrying the seeds and gel to the nozzle from which they are to be expelled into the ground nor to maintain spacing between seeds while moving them along the auger.
It is also known to use openers and planting shoes to prepare a furrow in which to deposit seeds. The prior art planting shoes have a disadvantage when used for fluid drilling in that there is insufficient space to permit accurate deposit of gel and seeds at a location protected by the shoe. In some prior art planters, additives such as growth stimulants, fungicides, herbicides and/or beneficial microorganisms are deposited separately from the seeds or coated onto the seeds or deposited in carrier materials. The prior art apparatus for applying additives generally deposit granules. These apparatuses have a disadvantage in that they waste expensive additives by applying them nonuniformly and at locations where they are not needed. Attempts to innoculate seeds with beneficial microorganisms other than Rhizobia have not been as successful as desired.